Conventionally, pulse compression radars which perform processing of transmitting a pulse with a predetermined width and compressing the pulse width in reception are known. With the pulse compression radars, there are cases where a signal amplified by an amplifier (e.g., a power amplifier) is transmitted. However, when the signal is amplified, nonlinear distortion may occur. As a method of correcting the nonlinear distortion, pre-distortion is known.
In the pre-distortion, by feeding back a portion of a signal to be externally transmitted, nonlinear distortion is acquired, and a correction of the signal is performed by taking the distortion into consideration. Specifically, correction data is obtained based on the acquired distortion, and based on the correction data, a transmission signal before being amplified is corrected beforehand so as to obtain an ideal waveform after the amplification by the amplifier. In the above manner, the distortion of the transmission signal can be removed.
Patent Document 1 discloses a wireless device which performs the pre-distortion. This wireless device stores previous correction data (distortion compensation coefficient) and calculates the correction data based on the previous correction data to update it. In Patent Document 1, an example in which a memory, such as a RAM (Random Access Memory) is used as a memory which stores the correction data is described.
Patent Document 2 discloses a wireless reception device which removes distortion in a reception circuit which receives a signal, instead of by performing pre-distortion. The wireless reception device includes an FIR digital filter which performs filtering on the received signal. The FIR digital filter is changeable of a coefficient, and the coefficient is stored in a non-volatile memory.